Methods for producing precursor solutions and sol-gels for nano-engineered carbon materials and nano-engineered carbon materials created therefrom

ABSTRACT

Methods of manufacturing nano-engineered carbon materials, such as carbon aerogels and carbon xerogels, and methods of manufacturing precursor solutions and sol-gels for making the same are provided. A method for manufacturing a precursor solution comprises programmed-addition of a cross-linking agent to a component mixture comprising a resorcinol compound. A method for manufacturing a sol-gel comprises subjecting a precursor solutions to at least one heat treatment. Methods for producing nano-engineered carbon materials from precursor solutions and sol-gels are also provided. Methods for using the nano-engineered carbon materials are also disclosed. The resulting nano-engineered carbon materials can be useful in a range of products including, supercapacitor applications, high-surface-area electrodes, fuel cells, and desalination systems.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of co-pending U.S. patent applicationSer. No. 13/157,029, filed on Jun. 9, 2011, which claims priority toU.S. Provisional Patent Application No. 61/352,965, filed on Jun. 9,2010, which are both incorporated by reference herein.

FIELD OF THE INVENTION

This application and the disclosures herein generally discuss and relateto methods for manufacturing of nano-engineered carbon materials, forexample, carbon aerogels and carbon xerogels.

BACKGROUND OF THE INVENTION

For many years, nano-engineered carbon materials such as carbon aerogelsand carbon xerogels have been used in a variety of products to improveproperties including, but not limited to, electrical conductivity andenergy storage in, for instance, supercapacitor applications. Certainqualities of nano-engineered carbon materials (e.g., carbon aerogels,carbon xerogels, carbon foams, carbon filter paper)—such as, forexample, electrical conductivity, low density, high surface area,controllable pore size, and high purity—are desirable in manyapplications, and thus nano-engineered carbon materials possessing thosequalities generally have high commercial value in the marketplace.

Methods for synthesizing nano-engineered carbon materials such as carbonaerogels and carbon xerogels on the laboratory scale are known in theart. Those methods may involve, for example, using resorcinol andformaldehyde for producing precursor solutions (e.g., a “sol,” which isa solution or a colloidal dispersion of particles in a liquid) forfurther processing into a sol-gel (e.g., a network in a continuousliquid phase or a colloidal suspension of particles that is gelled toform a solid) used for manufacturing nano-engineered carbon materials.However, the amount of chemical energy released from mixing theresorcinol (and all of its derivatives) with formaldehyde in thepresence of a catalyst and heat to create the precursor solution hasheretofore precluded large-scale manufacturing of nano-engineered carbonmaterials such as carbon aerogels and xerogels. Uncontrolled chemicalreactions with stored energy release capabilities may represent anincreased industrial explosion hazard, endangering employees and theenvironment, and raising the cost of manufacturing polymers.

Accordingly, there is a need for a method to sufficiently control therelease of chemical energy (measured, for instance, in exotherms) in themanufacturing of precursor solutions and sol-gels such that large-scaleproduction of nano-engineered carbon materials is possible. The improvedefficiency in manufacturing and increased safety (for example, bylowering the risk of container rupture or explosion) that can beachieved by controlling the release of chemical energy would be improvedcompared to conventional methods used to create nano-engineered carbonmaterials that are currently on the market.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 is a graph demonstrating the exotherm (BTU/lb-min) of a reactionbetween resorcinol and formaldehyde in the presence of a catalyst underadiabatic conditions.

FIG. 2 is a graph demonstrating the exotherm (BTU/lb-hr) of a reactionbetween resorcinol and formaldehyde in the presence of a catalyst withcooling.

FIG. 3 is a graph demonstrating the exotherm (BTU/lb-hr) of a reactionbetween resorcinol and formaldehyde in the presence of a catalyst, withcooling, using a programmed-addition of formaldehyde.

SUMMARY OF THE INVENTION

This application and the disclosures described herein generally relateto methods of manufacturing nano-engineered carbon materials, such ascarbon aerogels and carbon xerogels, and methods of manufacturingprecursor solutions and sol-gels for making the same. In one embodiment,a method for safely manufacturing a precursor solution on a large scale,approximately 10,000 lbs for example, comprises programmed-addition of across-linking agent to a component mixture comprising a resorcinolcompound. In another embodiment, a method for manufacturing a sol-gelcomprises subjecting the precursor solutions taught herein to at leastone heat treatment. Also disclosed generally herein are methods forproducing nano-engineered carbon materials from the precursor solutionsand sol-gels taught herein. Methods for using the nano-engineered carbonmaterials are also disclosed. The resulting nano-engineered carbonmaterials of the present disclosure can be useful in a range of productsincluding, but not limited to, supercapacitor applications,high-surface-area electrodes, fuel cells, and desalination systems.

DETAILED DESCRIPTION OF THE INVENTION Methods for Making a PrecursorSolution for a Nano-Engineered Carbon Material

Disclosed herein are methods for making precursor solutions fornano-engineered carbon materials. In one embodiment, a precursorsolution is used to make a nano-engineered carbon material. In anotherembodiment, a precursor solution is used to make a carbon aerogel. In afurther embodiment, a precursor solution is used to make a carbonxerogel. In yet another embodiment, a nano-engineered carbon material isany aerogel or xerogel with a framework primarily comprised of organicpolymers. In still another embodiment, a precursor solution is used tomake carbon foam. In still yet another embodiment, a precursor solutionis used to make carbon filter paper. One of ordinary skill in the artwill readily understand the uses and applications for the precursorsolutions taught herein.

Creating the Component Mixture

A precursor solution according to the present disclosure may be formedusing sol-gel chemistry processes. In some embodiments of the methodsdisclosed herein for making precursor solutions, at least one componentmixture is formed. In one embodiment, the at least one component mixturecomprises at least one resorcinol compound and water. In anotherembodiment, the at least one component mixture comprises at least oneresorcinol compound, water, and at least one catalyst. In yet anotherembodiment, the at least one component mixture comprises at least oneresorcinol compound, water, at least one catalyst, and at least oneadditive. One of ordinary skill in the art will readily understand thecomponent mixtures appropriate for making the precursor solutions taughtherein.

The at least one resorcinol compound may be any compound or derivativeof resorcinol now known or hereinafter discovered. The at least oneresorcinol compound may also be any compound from which resorcinol orany resorcinol derivative can be derived. In one embodiment, the atleast one resorcinol compound is resorcinol (i.e., benzene-1,3-diol,1,3-dihydroxybenzene). In another embodiment, the at least oneresorcinol compound is a derivative of resorcinol. In yet anotherembodiment, the at least one resorcinol compound is any compound fromwhich resorcinol can be derived. Appropriate resorcinol compounds foruse in the methods disclosed herein will be readily apparent to thoseskilled in the art.

In one embodiment, the at least one resorcinol compound is apolyhydroxybenzene. In another embodiment, the at least one resorcinolcompound is a dihydroxybenzene. In yet another embodiment, the at leastone resorcinol compound is a trihydroxybenzene. In still anotherembodiment, the at least one resorcinol compound is a substituted formof resorcinol.

In one embodiment, the at least one resorcinol compound is representedby the formula (I):

wherein R¹ is chosen from H, OH, C₁₋₅ alkyl, or OR³,wherein R² is chosen from H, OH, C₁₋₅ alkyl, or OR³,wherein R³ is chosen from C₁₋₅ alkyl or C₁₋₅ aryl, andwherein at least one of R¹ and R² is OH.

In another embodiment, the at least one resorcinol compound isrepresented by formula (II):

wherein each of R_(a), R_(b), R_(c), and R_(d) is independentlyhydrogen; hydroxy; halide such as fluoride, chloride, bromide or iodide;nitro; benzo; carboxy; acyl such as formyl, alkyl-carbonyl (e.g. acetyl)and arylcarbonyl (e.g. benzoyl); alkyl such as methyl, ethyl, propyl,butyl, pentyl, hexyl, heptyl, octyl, nonyl, decyl and the like; alkenylsuch as unsubstituted or substituted vinyl and allyl; unsubstituted orsubstituted methacrylate, unsubstituted or substituted acrylate; silylether; siloxanyl; aryl such as phenyl and naphthyl; aralkyl such asbenzyl; or alkaryl such as alkylphenyls, and wherein at least two ofR_(a), R_(c), and R_(d) is hydrogen.

Exemplary resorcinol compounds include, but are not limited to,resorcinol, phenol, catechol, hydroquinone, pyrogallol,5-methylresorcinol, 5-ethylresorcinol, 5-propylresorcinol,4-methylresorcinol, 4-ethylresorcinol, 4-propylresorcinol, resorcinolmonobenzoate, resorcinol monosinate, resorcinol diphenyl ether,resorcinol monomethyl ether, resorcinol monoacetate, resorcinol dimethylether, phloroglucinol, benzoylresorcinol, resorcinol rosinate, alkylsubstituted resorcinol, aralkyl substituted resorcinol,2-methylresorcinol, phloroglucinol, 1,2,4-benzenetriol,3,5-dihydroxybenzaldehyde, 2,4-dihydroxybenzaldehyde, 4-ethylresorcinol,2,5-dimethylresorcinol, 5-methylbenzene-1,2,3-triol, 3,5-dihydroxybenzylalcohol, 2,4,6-trihydroxytoluene, 4-chlororesorcinol,2′,6′-dihydroxyacetophenone, 2′,4′-dihydroxyacetophenone,3′,5′-dihydroxyacetophenone, 2,4,5-trihydroxybenzaldehyde,2,3,4-trihydroxybenzaldehyde, 2,4,6-trihydroxybenzaldehyde,3,5-dihydroxybenzoic acid, 2,4-dihydroxybenzoic acid,2,6-dihydroxybenzoic acid, 1,3-dihydroxynaphthalene,2′,4′-dihydroxypropiophenone, 2′,4′-dihydroxy-6′-methylacetophenone,1-(2,6-dihydroxy-3-methylphenyl)ethanone, 3-methyl3,5-dihydroxybenzoate, methyl 2,4-dihydroxybenzoate, gallacetophenone,2,4-dihydroxy-3-methylbenzoic acid, 2,6-dihydroxy-4-methylbenzoic acid,methyl 2,6-dihydroxybenzoate, 2-methyl-4-nitroresorcinol,2,4,5-trihydroxybenzoic acid, 3,4,5-trihydroxybenzoic acid,2,3,4-trihydroxybenzoic acid, 2,4,6-trihydroxybenzoic acid,2-nitrophloroglucinol or a combination thereof.

At least one catalyst may be used in the methods disclosed herein. Inone embodiment, the at least one catalyst is any catalyst now known orlater discovered to be suitable for the condensation reaction ofphenolic compounds with aldehydes. One of ordinary skill in the art willreadily understand the range of catalysts appropriate for practicing themethods disclosed herein. In one embodiment, the at least one catalystis a basic catalyst. Exemplary basic catalysts include, but are notlimited to metal oxides, such as sodium hydroxide, sodium carbonate,sodium bicarbonate, magnesium oxide, calcium oxide, barium oxide,zeolite, and potassium fluoride. In another embodiment, the at least onecatalyst is an acidic catalyst. Exemplary acidic catalysts include, butare not limited to, acetic acid, hydrochloric acid, sulfuric acid,phosphoric acid, phosphorous acid, and sulfonic acid (including but notlimited to monosulfonic acid, disulfonic acid, trisulfonic acid, toluenesulfonic acid, and alkane sulfonic acid). In one embodiment, the atleast one catalyst is acetic acid. In another embodiment, the at leastone catalyst is sodium carbonate. In one embodiment, the at least onecatalyst is used in an amount ranging from 0.01 to 10 parts per 100parts of the at least one resorcinol compound. In another embodiment,the molar ratio of the at least one resorcinol compound to catalyst is5:1.

The component mixture may additionally comprise at least one additive.Exemplary additives include, but are not limited to, sulfur, carbonblack, antioxidants, zinc oxide, accelerators, cellulose, filler,rheology modifiers, thickeners, surfactants, wetting agents, colorants,lubricants, leveling agents, UV stabilizers, plasticizers, silica,processing oils, softening oils, bloating agents, or mixtures thereof.In one embodiment, the at least one additive may be at least onesolvent. In one embodiment, the at least one solvent is organic. Inanother embodiment, the at least one solvent is inorganic. Exemplarysolvents include, but are not limited to, methyl alcohol, ethyl alcohol,n-propyl alcohol, isopropyl alcohol, butanol, acetone, tetrahydrofuran,benzene, toluene, xylene, ethylbenzene, cumene, mesitylene, or mixturesthereof. One of ordinary skill in the art would readily understand therange of additives that may be employed successfully in the methodsdisclosed herein.

In one embodiment, the component mixture is created at room temperature.In another embodiment, the component mixture is created at a temperatureranging from 20° C. to 25° C. In yet another embodiment, the componentmixture is created at a temperature ranging from 22° C. to 24° C. Instill another embodiment, the component mixture is created at atemperature below room temperature. In a further embodiment, thecomponent mixture is created at a temperature above room temperature.

Heating the Component Mixture

The component mixture may then be heated. In one embodiment, thecomponent mixture is heated to a temperature ranging from 10° C. to 100°C. In another embodiment, the component mixture is heated to atemperature from 30° C. to 99° C. In yet another embodiment, thecomponent mixture is heated to 50° C. In still another embodiment, thecomponent mixture is heated to 60° C. In a further embodiment, thecomponent mixture is heated to 70° C. In a further embodiment, thecomponent mixture is heated above 30° C., 40° C., 50° C., 60° C., or 70°C. One of ordinary skill in the art would readily understand appropriatetemperatures for use in practicing the methods disclosed herein.

Programmed-Addition of at Least One Cross-Linking Agent

In the methods disclosed herein, at least one cross-linking agent may beadded to the component mixture by programmed-addition, wherein thecross-linking agent is added to the component mixture at a controlledrate (either in batches or in a continuous stream) so that the reactionbetween the cross-linking agent and component mixture can be maintainedat a lower temperature level and resulting in a controlled exothermicreaction. In one embodiment, the at least one cross-linking agent is anyagent now known or herein after discovered capable of reacting with theat least one resorcinol compound to form a polymeric matrix. In anotherembodiment, the at least one cross-linking agent is any agent capable ofdonating methylene groups. In one embodiment, the methylene donorcompound is any compound capable of generating formaldehyde by heating.In another embodiment, the at least one cross-linking agent is analdehyde. Exemplary cross-linking agents include, but are not limitedto, formaldehyde, paraformaldehyde, trioxane, methyl formcel, n-butylformcel, acetaldehyde, propionaldehyde, ureaformaldehyde, methylolurea,hexamethylene tetramine, anhydroformaldehydeaniline, butyraldehyde,benzaldehyde crotanaldehyde, cinnamaldehyde, benzaldehyde, furfural,acetone, methyl ethyl ketone, hexamethylenetetramine,hexamethoxymethylmelamine, lauryloxymethylpyridinium chloride,ethyloxymethylpyridinium choride, trioxane hexamethylolmelamine,N-substituted oxymethylmelamines, alkyl aldehydes (including, but notlimited to n-butyraldehyde, isobutyraldehyde, and valeraldehyde),glyoxal, melamineformaldehyde, and mixtures thereof. In one embodiment,the at least one cross-linking agent is formaldehyde (i.e., menthanal).In another embodiment, the at least one cross-linking agent is a mixtureof formaldehyde and butyraldehyde. In some embodiments, the at least onecross-linking agent is mixed with water or an aqueous solvent. Inembodiments where a mixture of cross-linking agents is used, they can beadded to the reaction individually, simultaneously, or sequentially. Theat least one cross-linking agent may be used alone or in a mixture withan aqueous solvent (e.g., water or alcohols). In one embodiment, the atleast one cross-linking agent is a 50% formaldehyde solution in water.

In one embodiment, the at least one cross-linking agent is an aldehydeof formula (III):

R⁴—CH═O  (III)

wherein R⁴ is H, alkyl, alkenyl, substituted alkyl or substituted aryl.In one embodiment, the alkyl is a C₁₋₅ alkyl such as methyl, ethyl,propyl, isopropyl, butyl, isobutyl, or pentyl.

In one embodiment, the at least one cross-linking agent is anunsaturated aliphatic aldehyde compound. In another embodiment, the atleast one cross-linking agent is an unsaturated aliphatic aldehydecompound of formula (IV):

wherein R′, R″, and R′″ are individually a hydrogen or hydrocarbylgroup. In one embodiment, the hydrocarbyl group is branched. In anotherembodiment, the hydrocarbyl group is straight. Exemplary unsaturatedaliphatic aldehyde compounds include, but are not limited to,crotanaldehyde, acrolein, and methacrolein.

In yet another embodiment, the at least one cross-linking agent is analiphatic dialdehyde compound represented by formula (V):

O═CHCH₂_(n)═O  (V)

wherein “n” is a polymerization number providing the number of repeatunits in a polymer, is greater than or equal to 1. Exemplary aliphaticdialdehyde compounds include, but are not limited to, malonaldehyde,succinaldehyde, glutaraldehyde, and adipaldehyde.

The molar ratio of the at least one resorcinol compound to the at leastone cross-linking agent may be adjusted in the methods disclosed herein.In one embodiment, the molar ratio of the at least one resorcinolcompound to the at least one cross-linking agent ranges from 1:1 to 1:5.In another embodiment, the molar ratio ranges from 1:1.5 to 1:2.5. Inyet another embodiment, the molar ratio is 1:2. One of ordinary skill inthe art will readily understand the ranges of molar ratios appropriatefor use in the methods disclosed herein.

Once the necessary amount of the at least one cross-linking agent isselected, the cross linking agent may be added to the heated componentmixture by a programmed-addition method. In one embodiment, the at leastone cross-linking agent is divided into smaller batches such that whenthe batch of the at least one cross-linking agent reacts with the atleast one resorcinol compound, the maximum temperature increaseresulting from the reaction occurring in the mixing step will not exceed10° C. per minute. In another embodiment, once the at least onecross-linking agent is divided into batches, a batch of the at least onecross-linking agent is added to the heated component mixture. In yetanother embodiment, the maximum temperature increase resulting from thereaction occurring in the mixing step will not exceed at least one ofthe following 15° C., 10° C., 8° C., or 5° C. per minute. In yet anotherembodiment, the resulting solution is maintained at a reactiontemperature ranging from 30° C. to 99° C. using, for instance, coolingcoils. Then, in some embodiments, the remaining batches are addedstepwise to the solution, maintaining the reaction temperature rangingfrom 30° C. to 99° C. using, for instance, cooling coils. In oneembodiment, once all batches are added, the reaction temperature ismaintained at a temperature ranging from 30° C. to 99° C. until thereaction between the at least one resorcinol compound and the at leastone cross-linking agent is completed. In another embodiment, the atleast one cross-linking agent is added in a continuous feed such thatthe maximum increase resulting from the reaction between the at leastone resorcinol compound and the at least one cross-linking agent willnot exceed at least one of the following 15° C., 10° C., 8° C., or 5° C.per minute. In another embodiment, once the reaction is complete, thesolution is cooled. In yet another embodiment, the solution is cooled tostop the reaction at a time before at least one cross-linking agent andthe at least one resorcinol compound have reacted completely. The cooledsolution may then be stored for further processing.

During the programmed-addition of the at least one cross-linking agent,the temperature may be maintained at a reaction temperature. In oneembodiment, the reaction temperature is 50° C. In another embodiment,the reaction temperature is 60° C. In yet another embodiment, thereaction temperature ranges from 40° C. to about 80° C. In still anotherembodiment, the reaction temperature ranges from about 45° C. to about55° C.

The reaction temperature may be maintained by any means now known orhereinafter discovered for cooling or heating. In one embodiment, thereaction temperature is maintained by a heat exchanger. In anotherembodiment, the reaction temperature is maintained by cooling coils,heating coils, or a combination thereof. In yet another embodiment, thereaction temperature is maintained by a heating mantle. In still anotherembodiment, the reaction temperature is maintained by a combination ofheating devices and cooling devices. Those of ordinary skill in the artwill readily understand the available heating and cooling mechanismsthat may be employed to maintain the reaction temperature according tothe methods disclosed herein.

Optional Additional Steps

At least one alcohol may be added at any time during the production ofthe precursor solution. The addition of at least one alcohol may slowthe reaction rate of the mixture or may be used to prevent rapidhardening of the solution to a sol-gel. In one embodiment, the at leastone alcohol is methanol. In another embodiment, the at least one alcoholis a polyhydric alcohol such as, but are not limited to, diethyleneglycol, 1,2-propane diol, 1,4-butane diol, or 1,5-hexane diol. One ofordinary skill in the art will readily understand the appropriate rangeof alcohols that could be used successfully in the methods taughtherein.

The refractive index of the precursor solution varies with time.Monitoring the refractive index may help for determining the quality andconsistency of the properties in the final product. The refractive indexof the precursor solution may be monitored throughout the production ofthe precursor solution. One of ordinary skill in the art would readilyunderstand how to measure the refractive index of the precursorsolutions taught herein. In one embodiment, the reaction of the at leastone resorcinol compound and the at least one cross-linking agent isstopped when a refractive index measurement ranging from 1.4000 to1.4300 is obtained.

Methods of Making a Sol-Gel for Nano-Engineered Carbon Materials

Disclosed herein are methods for making a sol-gel for use in making, forexample, nano-engineered carbon materials. In one embodiment, a sol-gelis used to make a carbon aerogel. In another embodiment, a sol-gel isused to make a carbon xerogel. In yet another embodiment, a sol-gel isused to make any aerogel with a framework primarily comprised of organicpolymers. In still another embodiment a sol-gel is used to make a carbonfoam. In a further embodiment, a sol-gel is used to make a carbon filterpaper. One of ordinary skill in the art will readily understand uses ofthe sol-gels taught herein.

In one embodiment, the at least one nano-engineered carbon material isprepared through a sol-gel chemistry process. Appropriate sol-gelprocess techniques would be readily apparent to one of ordinary skill inthe art. The sol-gel process may begin with any solution containingsmall molecules with the ability to link together (i.e., polymerize) toform larger molecular clusters that could eventually grow intonanoparticles dispersed through the solution (i.e., a sol). Thosenanoparticles may then be coaxed into interconnecting (i.e.,cross-linking) to form a continuous network of interconnectednanoparticles that spans the volume of the liquid solution (i.e., asol-gel).

The sol-gels disclosed herein may be made by subjecting the precursorsolution, disclosed herein, to at least one heat treatment.

The at least one heat treatment may be selected to achieve a variety ofporosities in the sol-gels manufactured therefrom. In one embodiment,the at least one heat treatment involves sealing the precursor solutionin a container and heating it to a temperature ranging from 60° C. to99° C. in an oven for an amount of time ranging from 12 hours to 96hours. In another embodiment, the at least one heat treatment involvessealing the precursor solution in a container and heating it to 80° C.in an oven for 24 hours, resulting in a mesoporous sol-gel. In yetanother embodiment, the at least one heat treatment involves maintainingthe precursor solution at room temperature for 3-4 days and then placingit in an oven at 80° C. for 24 hours, resulting in a microporoussol-gel.

Methods of Making a Nano-Engineered Carbon Material

Disclosed herein are methods for making nano-engineered carbon materialsfrom the precursor solutions and sol-gels disclosed herein. In oneembodiment, the at least one nano-engineered carbon material is a carbonaerogel. In another embodiment, the at least one nano-engineered carbonmaterial is a carbon xerogel. In yet another embodiment, the at leastone nano-engineered carbon material is any aerogel or xerogel with aframework primarily comprised of organic polymers. In still anotherembodiment, the at least one nano-engineered carbon material is a carbonfoam. In still yet another embodiment, the at least one nano-engineeredcarbon material is a carbon filter paper.

Making a Nano-Engineered Carbon Material from a Sol-Gel

At least one nano-engineered carbon material may be made from thesol-gels disclosed herein. In one embodiment, the sol-gel is subject togrinding. In another embodiment, the sol-gel is subject to freezedrying. In yet another embodiment, the sol-gel is subject to cryogenicdrying in liquid nitrogen. In still another embodiment, the sol-gel issubject to pyrolysis. In a further embodiment, the sol-gel is subject tosupercritical drying. In another embodiment, the sol-gel is subject tovacuum drying. In still another embodiment, the sol-gel is subject toevaporation drying. In yet a further embodiment, the sol-gel is subjectto heating to a temperature ranging from 800° C. to 1000° C. Theabove-mentioned steps may be used alone or in combination with eachother or with other techniques known or hereinafter discovered formaking nano-engineered carbon materials.

In one embodiment, a carbon aerogel is formed from a sol-gel by: (1)grinding the sol-gel into chunks; (2) subjecting the ground sol-gel tofreeze-drying or supercritical drying; (3) using vacuum drying to expelthe water; (4) grinding the resulting solid into a fine powder; and (5)pyrolyzing the powder at inert conditions at a temperature ranging from800° C. to 1000° C. In another embodiment, a carbon xerogel is formedfrom a sol-gel by: (1) maintaining the sol-gel at room temperatureallowing the water to evaporate naturally from the sol-gel; (2) grindingthe resulting dried solid into a fine powder; and (3) pyrolyzing thepowder at inert conditions at a temperature ranging from 800° C. to1000° C. One of ordinary skill in the art would readily understand therange of methods and techniques that are appropriate for makingnano-engineered carbon materials from the sol-gels according to theinvention disclosed herein.

Properties of the at Least One Nano-Engineered Carbon Material

The at least one nano-engineered carbon material disclosed herein mayhave at least one advantageous property. In one embodiment, the at leastone nano-engineered carbon material is less friable than anano-engineered inorganic material such as an inorganic aerogel. Inanother embodiment, the at least one nano-engineered carbon material isless fragile than a nano-engineered inorganic material such as aninorganic aerogel.

The at least one nano-engineered carbon material disclosed herein may bemanufactured in a variety of densities. In one embodiment, the at leastone nano-engineered carbon material has a density of less than 0.02g/cm³. In another embodiment, the at least one nano-engineered carbonmaterial has a density ranging from 0.02 g/cm³ to 0.5 g/cm³. In yetanother embodiment, the at least one nano-engineered carbon material hasa density of at least 0.5 g/cm³.

The at least one nano-engineered carbon material disclosed herein may bemanufactured in a variety of surface areas. In one embodiment, the atleast one nano-engineered carbon material has a surface area rangingfrom 500 m²/g to 2500 m²/g.

The at least one nano-engineered carbon material disclosed herein may bemanufactured in a variety of electrical conductivities. The at least onenano-engineered carbon material disclosed herein may also bemanufactured in a variety of chemical purities. In one embodiment, theat least one nano-engineered carbon material is substantially free ofimpurities. In another embodiment, the at least one nano-engineeredmaterial is substantially free of metal ions. In yet another embodiment,the at least one nano-engineered carbon material is manufactured at ahigh enough level of purity for use in a high-voltage electrode.

The nano-engineered carbon materials disclosed herein may undergo atleast one additional processing step. In one embodiment, the at leastone additional processing step involves increasing the surface area ofthe at least one nano-engineered carbon material by placing it under aflow of steam or hydrogen at elevated temperatures (e.g., ranging from400° C. to 1000° C.). In that embodiment, the water and hydrogen reactwith carbon in the nano-engineered carbon material to form gaseousproducts and etch micropores throughout the interior of the aerogel toincrease the surface area of the at least one nano-engineered carbonmaterial. In one embodiment, the micropores are less than 4 nanometersin diameter. In another embodiment, the micropores are less than 2nanometers in diameter. In yet another embodiment, the micropores areless than 1 nanometer in diameter. In still another embodiment, the atleast one nano-engineered carbon material is mesoporous and has poresranging from 2 nanometers to 50 nanometers. In one embodiment, thesurface area of the at least one nano-engineered carbon material isincreased up to 2500 m²/g. In another embodiment, the surface area ofthe at least one nano-engineered carbon material is increased up to 2000m²/g. In yet another embodiment, the surface area of the at least onenano-engineered carbon material is increased up to 1500 m²/g.

Uses for Nano-Engineered Carbon Materials

The carbon aerogel products disclosed herein may be used in anyapplication now known to the skilled artisan or hereafter discovered.

Exemplary applications include, but are not limited to, electrodes,supercapacitors, fuel cells, composite materials, reinforcing agents,pigments, insulators, in media for gas separation or storage,controlled-release agent carriers, electro-chemical storage devices,catalysts, architectural daylighting, oil and gas pipelines, coatingsformulations, foams, papers, industrial and cryogenic plants andvessels, outdoor gear and apparel, and personal care products.

Unless otherwise indicated to the contrary, all numbers expressingquantities of ingredients, reaction conditions, and so forth used in thespecification, including claims, are to be understood as being modifiedin all instances by the term “about.” Accordingly, unless indicated tothe contrary, the numerical parameters set forth in the specificationand attached claims are approximations that may vary depending upon thedesired properties sought to be obtained by the present disclosure. Atthe very least, and not as an attempt to limit the application of thedoctrine of equivalents to the scope of the claims, each numericalparameter should be construed in light of the number of significantdigits and ordinary rounding approaches.

Notwithstanding that the numerical ranges and parameters setting forththe broad scope of the disclosure are approximations, unless otherwiseindicated the numerical values set forth in the specific examples arereported as precisely as possible. Any numerical values, however,inherently contain certain errors necessarily resulting from thestandard deviation found in their respective testing measurements. Thesection headings used in this disclosure are provided merely for theconvenience of the reader and are not intended to limit the scope of theinventions described herein.

Other embodiments of the disclosure will be apparent to those skilled inthe art from consideration of the specification and practice of theinventions disclosed herein. It is intended that the specification andexamples be considered as exemplary only, with a true scope and spiritof the disclosure being indicated by the following claims.

In one embodiment, the present invention is:

1. A method of producing a precursor solution comprising:

creating at least one component mixture comprising water, at least oneresorcinol compound, and at least one catalyst;

heating the at least one component mixture to a temperature ranging from30° C. to 99° C. to create a heated component mixture; and

adding at least one cross-linking agent to the heated component mixtureby a programmed-addition method comprising:

-   -   an optional dividing step, wherein the at least one        cross-linking agent is divided into batches;    -   a mixing step, wherein a solution is created by adding one of a        plurality of batches of the at least one cross-linking agent to        the heated component mixture;    -   a cooling step, wherein the solution is cooled to a temperature        ranging from 30° C. to 99° C.;    -   an optional repeating step, wherein the mixing and cooling steps        are repeated as necessary to consume all of the remaining of the        plurality of batches of the at least one cross-linking agent to        create a final solution; and    -   wherein each batch comprises an amount of the at least one        cross-linking agent sufficient to prevent the maximum        temperature increase resulting from the reaction occurring in        the mixing step from exceeding 10° C. per minute;

maintaining the temperature of the final solution at a temperatureranging from 45° C. to 55° C. for an amount of time ranging from 15minutes to 480 minutes; and

cooling the final solution to a temperature of less than 40° C.

2. The method of any of the preceding paragraphs, wherein the at leastone component mixture is mixed at a temperature ranging from 20° C. to25° C.

3. The method of any of the preceding paragraphs, wherein the at leastone resorcinol compound is represented by the formula (I):

wherein each R_(a), R_(b), R_(c), and R_(d) is independently selectedfrom a group consisting of: hydrogen; hydroxy; a halide such asfluoride, chloride, bromide or iodide; nitro; benzo; carboxy; acyl suchas formyl, alkyl-carbonyl (e.g. acetyl) and arylcarbonyl (e.g. benzoyl);alkyl such as methyl, ethyl, propyl, butyl, pentyl, hexyl, heptyl,octyl, nonyl, decyl and the like; alkenyl such as unsubstituted orsubstituted vinyl and allyl; unsubstituted or substituted methacrylate,unsubstituted or substituted acrylate; silyl ether; siloxanyl; aryl suchas phenyl and naphthyl; aralkyl such as benzyl; or alkaryl such asalkylphenyls; and wherein at least two of R_(a), R_(c), and R_(d) ishydrogen.

4. The method of any of the preceding paragraphs, wherein the at leastone resorcinol compound is benzene-1,3-diol.

5. The method of any of the preceding paragraphs, wherein the at leastone resorcinol compound is chosen from phenol, derivatives of phenol, orphenol and its derivatives.

6. The method of any of the preceding paragraphs, wherein the at leastone catalyst is acetic acid.

7. The method of any of the preceding paragraphs, wherein the at leastone cross-linking agent is selected from a group consisting of:formaldehyde, paraformaldehyde, trioxane, methyl formcel, acetaldehyde,propionaldehyde, butyraldehyde, crotanaldehyde, cinnamaldehyde,benzaldehyde, furfural, acetone, methyl ethyl ketone, and mixturesthereof.

8. The method of any of the preceding paragraphs, wherein the at leastone cross-linking agent is formaldehyde.

9. The method of any of the preceding paragraphs, wherein the molarratio of the at least one resorcinol compound to the at least onecross-linking agent ranges from 1:1 to 1:3.

10. The method of any of the preceding paragraphs, wherein the componentmixture is heated to at least 40° C.

11. The method of any of the preceding paragraphs, wherein the componentmixture is heated to 50° C.

12. The method of any of the preceding paragraphs, wherein the componentmixture is heated to at least 60° C.

13. The method of any of the preceding paragraphs, wherein the at leastone cross-linking agent is added as a continuous feed in the mixingstep.

14. The method of any of the preceding paragraphs, wherein the at leastone cross-linking agent is added as a multi-step batch addition in themixing step.

15. The method of any of the preceding paragraphs, further comprisingthe addition of at least one alcohol.

16. The method of any of the preceding paragraphs, wherein the at leastone alcohol is methanol.

17. The method of any of the preceding paragraphs, further comprisingshining a light into the reactor to monitor the completion of thereaction by measuring the refractive index of the materials.

18. A method for making a sol-gel comprising:

preparing a precursor solution according to claim 0; and

subjecting the precursor solution to at least one heat treatment at atemperature ranging from 60° C. to 99° C. for an amount of time rangingfrom 12 hours to 96 hours.

19. The method of any of the preceding paragraphs, wherein the at leastone heat treatment comprises heating the precursor solution to atemperature ranging from 60° C. to 99° C. for 24 to 48 hours, said atleast one heat treatment resulting in the formation of a mesoporoussol-gel.

20. The method of any of the preceding paragraphs, wherein the at leastone heat treatment comprises:

maintaining the precursor solution at a temperature ranging from 10° C.to 40° C. for 1 to 30 days; and

heating the precursor/pregelled solution to a temperature ranging from60° C. to 99° C. for 24 to 96 hours, said at least one heat treatmentresulting in the formation of a microporous sol-gel.

21. A method for making a nano-engineered carbon material comprising:

preparing a sol-gel according to claim Error! Reference source notfound;

subjecting the sol-gel to at least additional treatment.

22. The method of any of the preceding paragraphs, wherein the at leastone additional treatment comprises grinding, freeze drying, cryogenicdrying, supercritical drying, vacuum drying, evaporation drying,pyrolysis, or a combination thereof.

23. The method of any of the preceding paragraphs, wherein the resultingnano-engineered carbon material is a carbon aerogel.

24. The method of any of the preceding paragraphs, wherein the resultingnano-engineered carbon material is a carbon xerogel.

By way of non-limiting illustration, examples of certain embodiments ofthe present disclosure are given below.

EXAMPLES Example 1 (Comparative) Dumping all Formaldehyde UnderAdiabatic Conditions

The first example is a comparative example illustrating a reaction ofresorcinol and formaldehyde in the presence of a catalyst at adiabaticconditions. First, a reaction kettle with a mechanical stirrer andthermometer was added with 802.2 grams of water. Then, 59.2 grams ofglacial acetic acid (supplied by Fisher Scientific, Inc.) was added tothe reaction kettle, while the mixture was being stirred (i.e., understirring), at room temperature. Next, 544.8 grams of resorcinol(supplied by Sigma-Aldrich, Inc.) were then added to the reaction kettleunder stirring. The addition of resorcinol caused an endothermicdecrease in temperature. At this point, the refractive index wasmeasured by a refractometer (supplied by Bellingham Stanley Ltd., Model#RRM330) to be 1.4025.

Then, the reaction mixture was slowly heated to reach a temperature of50° C. As soon as the temperature reached 50° C., 593.8 grams of theformaldehyde (50% solution in water stored at 50° C., supplied byGeorgia-Pacific) was added quickly under stirring. At this point, therefractive index was measured by a refractometer (supplied by BellinghamStanley Ltd., Model #RRM330) to be 1.4184.

After the addition of the formaldehyde, the temperature of the reactionwas recorded every minute. To get complete exotherm information, thereaction was allowed to proceed until gelation. Then, the refractiveindex was measured by a refractometer (supplied by Bellingham StanleyLtd., Model #RRM330) to be 1.4297. The results of that experiment areshown in Table 1.

TABLE 1 Temperature and Exotherm Data for the Reaction BetweenResorcinol and Formaldehyde Under Adiabatic Conditions Time afterformaldehyde Tem- Heat Exotherm Clock addition perature Capacity (BTU/Kick Time (min) (° C.) (cal/gm-C.) lb-min) Point 12:10 PM  Heating 12:15PM  ″ 12:20 PM  ″ 1:38 PM ″ 1:39 PM 0 50.2 0.79 64 1:40 PM 1 50.4 0.790.3 64 1:42 PM 2 50.4 0.79 0.0 64 1:43 PM 3 50.6 0.79 0.3 64 1:44 PM 451.2 0.79 0.9 64 1:45 PM 5 51.6 0.79 0.6 64 1:46 PM 6 52.3 0.79 1.0 641:47 PM 7 52.9 0.79 0.9 64 1:48 PM 8 53.4 0.79 0.7 64 1:49 PM 9 54.10.79 1.0 64 1:50 PM 10 54.7 0.79 0.9 64 1:51 PM 11 55.4 0.79 1.0 64 1:52PM 12 56.1 0.79 1.0 64 1:53 PM 13 56.9 0.79 1.1 64 1:54 PM 14 57.7 0.791.1 64 1:55 PM 15 58.6 0.79 1.3 64 1:56 PM 16 59.6 0.79 1.4 64 1:57 PM17 60.6 0.79 1.4 64 1:58 PM 18 61.7 0.81 1.6 64 1:59 PM 19 62.8 0.81 1.664 2:00 PM 20 64.2 0.81 2.1 64 2:01 PM 21 65.6 0.81 2.1 2:02 PM 22 67.30.81 2.5 2:03 PM 23 69.1 0.81 2.6 2:04 PM 24 71.2 0.81 3.1 2:05 PM 2573.6 0.81 3.5 2:06 PM 26 76.4 0.81 4.1 2:07 PM 27 79.6 0.85 4.9 2:08 PM28 83.3 0.85 5.7 2:09 PM 29 87.7 0.85 6.7 2:10 PM 30 92.7 0.85 7.6 2:11PM 31 98.6 0.85 9.0

The exotherm value was observed in the range of 0.3 to 9.0 BTU/lb-min(or 18 to 540 BTU/lb-hr). FIG. 1 demonstrates the results of thisexperiment. As can be seen in FIG. 1, the graph showed higher slopeabove 64° C. (the kick point), showing that the exotherm is much higherwhen the temperature goes above 64° C.

Example 2 (Comparative) Dumping all Formaldehyde Under CoolingConditions

First, accurate coil flow rate data was obtained using a peristalticpump equipped with a precision speed control (MASTERFLEX® 7521-40), witha MASTERFLEX® Easy Load head (Model 7518-12) and ¼′″ ID TYGON® tubingwas used to deliver cooling water to the reactor coils. The pump wascalibrated by pumping water for three minutes at a given setting on the10-turn speed control dial and collecting the water. The water collectedwas weighed and the rate of grams of water per minute was calculated.The pump was found to be linear over a range of settings that resultedin flow rates from about 200 grams per minute to over 1300 grams perminute.

A reaction kettle with mechanical stirrer, thermometer, and internalcooling coils had 802.2 grams of water added to it. Then, 59.2 grams ofGlacial acetic acid (supplied by Fisher Scientific, Inc.) was addedunder stirring at room temperature. Next, 544.8 grams of resorcinol(supplied by Sigma-Aldrich, Inc.) was added to the reaction kettle understirring. The addition of resorcinol caused an endothermic decrease intemperature. The refractive index was measured using a refractometer(supplied by Bellingham Stanley Ltd, Model #RFM330) to be 1.4205.

The reaction mixture was heated slowly to reach a temperature of 50° C.Without adjusting the heating, the reaction temperature was maintainedat 50° C. by cooling water passing through internal cooling coils. Thetemperature of water going into and coming out of the cooling coils wasrecorded by a computer connected to a temperature probe. Thetemperatures were recorded as inlet and outlet temperatures,respectively.

At 50° C., 593.8 grams of formaldehyde (50% solution in water stored at50° C., supplied by Georgia-Pacific) was added quickly under stirring.After the addition of formaldehyde, the temperature of the reaction wasrecorded every minute. The refractive index was measured using arefractometer (supplied by Bellingham Stanley Ltd, Model #RFM330) to be1.4184. To get complete exotherm information, the reaction was allowedto react until gelation, or formation of a gel. The results of thisexperiment are shown in Table 2.

TABLE 2 Temperature and Exotherm Data for the Reaction BetweenResorcinol and Formaldehyde Under Cooling Conditions Batch Inlet OutletData Pt Time Temperature Temperature Temperature Coil Flow Rate Avg'dRxn Heating sec min deg C. deg C. deg C. grams/min lb/hr BTU/lb-hr Avg50.66 20.60 47.21 267.62 35.368 45 1380 23 50.63 20.61 47.49 244.0032.247 14 1440 24 50.58 20.31 47.72 259.00 34.229 43 1500 25 50.82 20.2647.79 259.00 34.229 45 1560 26 50.72 20.51 47.12 259.00 34.229 32 162027 50.72 20.75 47.87 259.00 34.229 39 1680 28 50.82 20.90 47.27 275.0036.344 52 1740 29 50.92 20.90 48.16 275.00 36.344 65 1800 30 50.77 20.7047.42 275.00 36.344 57 1860 31 50.68 20.31 47.12 275.00 36.344 58 192032 50.68 20.56 47.12 275.00 36.344 55 1980 33 50.68 20.36 47.12 275.0036.344 57 2040 34 50.23 20.65 46.52 275.00 36.344 44 2100 35 50.13 20.4646.37 275.00 36.344 45 2160 36 50.48 20.70 46.67 269.00 35.551 37 222037 50.13 20.56 46.97 269.00 35.551 44 2280 38 50.58 20.51 47.94 269.0035.551 59 2340 39 50.92 20.75 47.72 269.00 35.551 52 2400 40 50.63 20.9047.72 269.00 35.551 50 2460 41 50.68 20.80 47.42 269.00 35.551 47 252042 50.82 20.85 47.34 272.00 35.947 49 2580 43 50.82 20.65 47.42 272.0035.947 53 2640 44 50.92 20.65 47.72 272.00 35.947 58 2700 45 50.72 20.5147.04 272.00 35.947 50 2760 46 50.72 20.56 47.34 272.00 35.947 54 282047 50.68 20.61 47.64 272.00 35.947 57 2880 48 50.72 20.56 47.49 272.0035.947 56 2940 49 50.63 20.80 47.64 272.00 35.947 54 3000 50 51.07 20.7547.42 272.00 35.947 52 3060 51 50.82 20.70 47.12 272.00 35.947 48 312052 50.77 20.75 47.12 272.00 35.947 47 3180 53 50.77 20.51 47.42 272.0035.947 55 3240 54 50.48 20.80 47.27 272.00 35.947 49 3300 55 50.97 20.5142.03 272.00 35.947 51 3360 56 50.68 20.36 47.12 272.00 35.947 53 342057 50.63 20.65 47.34 272.00 35.947 52 3480 58 50.68 20.41 47.19 272.0035.947 53

By maintaining the temperature of the reaction at 50° C., the exothermvalue was observed in the range of 14 to 64 BTU/lb-hr. FIG. 2demonstrates the results of this experiment. As can be seen in FIG. 2and Table 2, the range of exotherm values is lower than the reactionthat was allowed to run without cooling in Example 1.

Example 3 (Inventive) Reaction of Resorcinol and Formaldehyde in thePresence of a Catalyst Under Cooling Conditions with aProgrammed-Addition of Formaldehyde

To obtain accurate coil flow rate data, a peristaltic pump equipped witha precision speed control (MASTERFLEX® 7521-40), with a MASTERFLEX® EasyLoad head (Model 7518-12) and ¼′″ ID TYGON® tubing was used to delivercooling water to the DAQ reactor coils. The pump was calibrated bypumping water for three minutes at a setting on the 10-turn speedcontrol dial and collecting the water. The water collected was weighedand the rate of grams of water per minute was calculated. The pump wasfound to be linear over a range of settings that resulted in flow ratesfrom about 200 grams per minute to over 1300 grams per minute.

Then, a reaction kettle with mechanical stirrer, thermometer, andinternal cooling coils was added with 802.2 grams of water. Then, 59.2grams of Glacial acetic acid (supplied by Fisher Scientific, Inc.) wasadded under stirring at room temperature. Next, 544.8 grams ofresorcinol (supplied by Sigma-Aldrich, Inc.) was added to a reactionvessel under stirring. The addition of resorcinol caused an endothermicdecrease in temperature. At this point, the refractive index wasmeasured by a refractometer (supplied by Bellingham Stanley Ltd., Model#RRM330) to be 1.4205

The reaction mixture was heated slowly to reach temperature of 50° C.With the same heating rate, the reaction temperature was maintained at50° C. by cooling water passing through internal cooling coils. Thetemperature of water going into and coming out of coils was recorded bya computer connected to a temperature probe. The respective temperatureswere recorded as inlet and outlet temperatures.

At 50° C., the addition of 593.8 grams of formaldehyde (50% solution inwater stored at 50° C., supplied by Georgia-Pacific) started at a rateof 10 mL/min. During the addition of formaldehyde, the temperature ofthe reaction was recorded every minute.

In order to get complete exotherm information the reaction was allowedto react until gelation. At this point, the refractive index wasmeasured by a refractometer (supplied by Bellingham Stanley Ltd., Model#RRM330) to be 1.4184. The results of this experiment are shown in Table3.

TABLE 3 Temperature and Exotherm Data for the Reaction BetweenResorcinol and Formaldehyde Under Cooling Conditions with theProgrammed-Addition of Formaldehyde Batch Inlet Outlet Avg AccumulatedData Pt Time Temperature Temperature Temperature Coil Flow Rate CoilFlow Rate Rxn Heating Batch sec min deg C. deg C. deg C. grams/min lb/hrBTU/lb-hr Lbs bold range avg 50.61 20.76 47.96 244.65 32.333 19 2400 4050.18 20.65 47.57 215.00 28.414 −27 2460 41 50.28 20.56 47.72 224.0029.604 −11 2520 42 50.38 20.85 47.72 224.00 29.604 −15 2580 43 50.4320.61 48.09 224.00 29.604 −7 2640 44 50.92 20.65 48.24 224.00 29.604 −62700 45 50.97 20.65 48.69 224.00 29.604 −1 2760 46 51.36 20.65 48.84224.00 29.604 1 2820 47 51.36 20.90 48.31 224.00 29.604 0 zero'd 2880 4851.61 20.95 47.87 234.00 30.925 0 2940 49 51.66 20.75 47.94 234.0030.925 21 4.195301 3000 50 51.66 20.70 48.69 234.00 30.925 30 4.2143913060 51 51.76 20.65 48.54 234.00 30.925 27 4.23348 3120 52 51.81 21.0948.31 234.00 30.925 17 4.25257 3180 53 51.61 20.61 48.54 257.00 33.96559 4.271659 3240 54 51.36 20.80 48.76 257.00 33.965 57 4.290749 3300 5551.17 21.04 48.61 257.00 33.965 50 4.309838 3360 56 50.92 21.04 48.24257.00 33.965 43 4.328928 3420 57 51.02 20.46 47.79 257.00 33.965 454.348018 3480 58 50.68 20.56 47.87 257.00 33.965 40 4.367107 3540 5950.72 20.46 47.72 257.00 33.965 40 4.386197 3600 60 50.38 20.31 47.34257.00 33.965 33 4.405286 3660 61 50.04 20.12 47.04 257.00 33.965 323720 62 49.94 20.26 47.12 257.00 33.965 32 3780 63 50.04 20.31 47.27257.00 33.965 35 3840 64 49.64 20.12 46.82 257.00 33.965 28 3900 6549.30 20.31 46.89 257.00 33.965 27 3960 66 49.40 20.36 47.04 257.0033.965 31 4020 67 49.79 20.41 47.34 234.00 30.925 3 4080 68 50.23 20.3647.42 234.00 30.925 5 4140 69 50.63 20.56 47.57 234.00 30.925 4 4200 7050.72 20.70 44.65 234.00 30.925 −37 4260 71 50.92 20.65 47.72 234.0030.925 3 4320 72 50.92 20.85 48.01 234.00 30.925 3 4380 73 51.27 20.7548.16 234.00 30.925 9 4440 74 51.27 20.41 48.39 247.00 32.643 33 4500 7550.92 20.85 48.01 247.00 32.643 20 4560 76 50.92 20.51 48.01 247.0032.643 27 4620 77 51.02 20.75 47.72 247.00 32.643 20 4680 78 50.82 20.8048.01 247.00 32.643 22 4740 79 50.97 20.61 47.87 247.00 32.643 25 480080 50.77 20.80 47.79 247.00 32.643 19 4860 81 50.53 20.46 47.79 247.0032.643 23 4920 82 50.38 20.80 47.87 247.00 32.643 20 4980 83 50.53 21.0047.49 247.00 32.643 14 5040 84 50.33 20.70 47.57 247.00 32.643 17 510085 50.33 21.04 47.42 247.00 32.643 12 5160 86 50.68 20.61 48.01 247.0032.643 28 5220 87 50.33 20.61 47.94 247.00 32.643 23 5280 88 50.38 20.8047.64 247.00 32.643 18 5340 89 50.53 20.90 47.94 247.00 32.643 22 540090 50.48 20.90 48.16 247.00 32.643 23 5460 91 50.48 20.90 48.16 247.0032.643 24 5520 92 50.48 20.90 48.16 247.00 32.643 24 5580 93 50.48 20.9048.16 247.00 32.643 24 5640 94 50.48 20.90 48.16 247.00 32.643 24 570095 50.48 20.90 48.16 247.00 32.643 24 5760 96 50.48 20.90 48.16 247.0032.643 24 5820 97 50.48 20.90 48.16 247.00 32.643 24 5880 98 50.48 20.9048.16 247.00 32.643 24 5940 99 50.48 20.90 48.16 247.00 32.643 24 6000100 50.48 20.90 48.16 247.00 32.643 24 6060 101 50.48 20.90 48.16 247.0032.643 24 6120 102 50.48 20.90 48.16 247.00 32.643 24 6180 103 50.4820.90 48.16 247.00 32.643 24 6240 104 50.48 20.90 48.16 247.00 32.643 246300 105 50.48 20.90 48.16 247.00 32.643 24 6360 106 50.48 20.90 48.16247.00 32.643 24 6420 107 50.48 20.90 48.16 247.00 32.643 24 6480 10850.48 20.90 48.16 247.00 32.643 24 6540 109 50.48 20.90 48.16 247.0032.643 24 6600 110 50.48 20.90 48.16 247.00 32.643 24 6660 111 50.4820.90 48.16 247.00 32.643 24 6720 112 50.48 20.90 48.16 247.00 32.643 246780 113 50.48 20.90 48.16 247.00 32.643 24 6840 114 50.48 20.90 48.16247.00 32.643 24 6900 115 50.48 20.90 48.16 247.00 32.643 24 6960 11650.48 20.90 48.16 247.00 32.643 24 7020 117 50.48 20.90 48.16 247.0032.643 24 7080 118 50.48 20.90 48.16 247.00 32.643 24 7140 119 50.4820.90 48.16 247.00 32.643 24 7200 120 50.48 20.90 48.16 247.00 32.643 247260 121 50.48 20.90 48.16 247.00 32.643 24 7320 122 50.48 20.90 48.16247.00 32.643 24 7380 123 50.48 20.90 48.16 247.00 32.643 24 7440 12450.48 20.90 48.16 247.00 32.643 24 7500 125 50.48 20.90 48.16 247.0032.643 24 7560 126 50.48 20.90 48.16 247.00 32.643 24 7620 127 50.4820.90 48.16 247.00 32.643 24 7680 128 50.48 20.90 48.16 247.00 32.643 24

By maintaining the temperature of the reaction at 50° C. and addingformaldehyde by a programmed-addition method, the exotherm value wasobserved in the range of 5 to 30 BTU/lb-hr. FIG. 3 illustrates theresults of this experiment. This range is much lower than the reactionthat was allowed to run either without cooling and without theprogrammed-addition of formaldehyde (Example 1) or with cooling butwithout the programmed-addition of formaldehyde (Example 2).

Thus, those three examples demonstrate that the process of controllingthe exotherm of the reaction between resorcinol and formaldehyde byprogrammed-addition of formaldehyde could be useful for large productionof precursor solutions on an industrial scale.

The exotherm value for the uncontrolled reaction was observed in therange of 18 to 540 BTU/lb-hr. By maintaining the temperature of reactionat 50° C., the exotherm value was observed in the range of 14 to 64BTU/lb-hr. Whereas, keeping the temperature of the reaction at 50° C.and adding formaldehyde by programmed-addition, the exotherm value wasobserved in the range of 5 to 30 BTU/lb-hr.

Also, it was observed that stopping at a specific defined refractiveindex helps to make the reaction consistent in terms of molecular weightand branching. According to an embodiment of this invention, the rangeof 1.4000 to 1.4300 for refractive indices has been identified to stopthe reaction in order to obtain a consistent product.

What is claimed is:
 1. A method for producing a precursor solution,comprising: adding a cross-linking agent to a first mixture comprisingwater, a resorcinol compound, and a catalyst to produce a secondmixture; reacting the resorcinol compound and the cross-linking agent toproduce a precursor solution; and maintaining a reaction temperature ofthe resorcinol compound and the cross-linking agent at 40° C. to 99° C.2. The method of claim 1, wherein the reaction temperature is 40° C. to80° C.
 3. The method of claim 1, wherein the reaction temperature is 45°C. to 55° C.
 4. The method of claim 1, wherein the resorcinol compoundand the cross-linking agent are reacted at a molar ratio of 1:1.5 to1:2.5.
 5. The method of claim 1, wherein the precursor solution has arefractive index of 1.4000 to 1.4300.
 6. The method of claim 1, whereinthe resorcinol compound is represented by formula (I):

wherein each R_(a), R_(b), R_(c) and R_(d) is independently selectedfrom the group consisting of: hydrogen; hydroxy; a halide; nitro; benzo;carboxy; acyl; alkyl; alkenyl; unsubstituted or substitutedmethacrylate; unsubstituted or substituted acrylate; silyl ether;siloxanyl; aryl; aralkyl; and alkaryl; and wherein at least two ofR_(a), R_(c), and R_(d) are hydrogen.
 7. The method of claim 1, whereinthe cross-linking agent comprises formaldehyde, paraformaldehyde, atrioxane, acetaldehyde, propionaldehyde, butyraldehyde, crotonaldehyde,cinnamaldehyde, benzaldehyde, furfural, acetone, methyl ethyl ketone, orany mixture thereof.
 8. The method of claim 1, wherein the catalystcomprises acetic acid, hydrochloric acid, sulfuric acid, phosphoricacid, phosphorous acid, a sulfonic acid, or any mixture thereof.
 9. Themethod of claim 1, wherein the reaction temperature is 40° C. to 80° C.;the resorcinol compound comprises benzene-1,3-diol, phenol, or a mixturethereof; the cross-linking agent comprises formaldehyde; and thecatalyst comprises acetic acid.
 10. The method of claim 1, wherein thefirst mixture, the second mixture, or both the first mixture and thesecond mixture further comprise an alcohol that comprises methanol,diethylene glycol, 1,2-propane diol, 1,4-butane diol, 1,5-hexane diol,or any mixture thereof.
 11. The method of claim 1, further comprising:cooling the precursor solution to a temperature of less than 40° C. toproduce a cooled precursor solution; and heating the cooled precursorsolution to a temperature of 60° C. to 99° C. for 12 hours to 96 hoursto produce a sol-gel.
 12. The method of claim 1, further comprising:cooling the precursor solution to a temperature of less than 40° C. toproduce a cooled precursor solution; sealing the cooled precursorsolution in a container; and heating the precursor solution in thesealed container to a temperature of 60° C. to 99° C. for 12 hours to 96hours to produce a sol-gel.
 13. A method for producing a precursorsolution, comprising: heating a first mixture comprising water, aresorcinol compound, and an acidic catalyst to a temperature of about30° C. to 99° C. to produce a heated mixture; adding a cross-linkingagent to the heated mixture to produce a second mixture; reacting theresorcinol compound and the cross-linking agent in the second mixture toproduce a precursor solution; maintaining a reaction temperature of theresorcinol compound and the cross-linking agent at 40° C. to 99° C.;cooling the precursor solution to a temperature of less than 40° C. toproduce a cooled precursor solution; and heating the cooled precursorsolution to a temperature of 60° C. to 99° C. for 12 hours to 96 hoursto produce a sol-gel.
 14. The method of claim 13, wherein the reactiontemperature is 40° C. to 80° C.
 15. The method of claim 13, wherein thecross-linking agent is added to the heated mixture as a continuous feed.16. The method of claim 13, wherein the cross-linking agent is added tothe heated mixture as a plurality of batches.
 17. The method of claim13, wherein the reaction temperature is 40° C. to 80° C.; the resorcinolcompound comprises benzene-1,3-diol, phenol, or a mixture thereof; thecross-linking agent comprises formaldehyde; the acidic catalystcomprises acetic acid; and the precursor solution has a refractive indexof 1.4000 to 1.4300.
 18. The method of claim 13, wherein the reactiontemperature does not exceed 80° C.
 19. The method of claim 13, whereinthe sol-gel is a microporous sol-gel or a mesoporous sol-gel.
 20. Amethod for producing a carbon aerogel or a carbon xerogel, comprising:heating a first mixture comprising water, a resorcinol compound, and anacidic catalyst to a temperature of about 30° C. to 99° C. to produce aheated mixture, wherein the resorcinol compound comprisesbenzene-1,3-diol, phenol, or a mixture thereof; adding formaldehyde tothe heated mixture to produce a second mixture; maintaining the secondmixture at a temperature of 40° C. to 99° C.; reacting the resorcinolcompound and the formaldehyde to produce a precursor solution;maintaining a reaction temperature of the resorcinol compound and theformaldehyde at 40° C. to 99° C.; cooling the precursor solution to atemperature of less than 40° C. to produce a cooled precursor solution;heating the cooled precursor solution to a temperature of 60° C. to 99°C. for 12 hours to 96 hours to produce a sol-gel; and subjecting thesol-gel to one or more additional treatments to produce a carbon aerogelor a carbon xerogel, wherein the one or more additional treatmentscomprise grinding, freeze drying, cryogenic drying, supercriticaldrying, vacuum drying, evaporation drying, pyrolysis, or any combinationthereof.